1. Field of the Invention
The present invention is based on Korean Application No. 98-33283 filed on Aug. 17, 1998, which is incorporated herein by reference, and relates to an inter-network communications method, and more particularly, to a method of forming a shortcut between networks, by which data is transferred via the shortest route along a preset data transfer path during transfer of data between different networks.
2. Description of the Related Art
FIG. 1 shows the configuration of a gateway for connecting a conventional IEEE 1394 to an asynchronous transfer mode (ATM). In the ATM transfer method, data transmitted via a communication line is divided into small pieces called cells, and the cells are transferred at high speed in an asynchronous system. The ATM transfer method is usually used in broadband ISDN environments to transfer large-capacity multimedia information including images and sounds. With multimedia communications services increasing, the ATM transfer method is highly regarded as a means for high-speed data communications.
A gateway is a device for connecting a local area network (LAN) to another communications network. That is, the gateway is used to connect two different LANs to each other or to connect a LAN to an external long distance network.
Generally, a variety of communication networks are used throughout the world, and each has a unique system. That is, each communication network uses a unique data format and a unique communication protocol. Since direct transfer of data from one network to another network is impossible due to the differences in data format and protocol between the networks, a gateway is connected between the two networks as a mediator for solving the transfer difference between the two networks.
IEEE 1394 (hereinafter referred to as 1394), which is a high-speed serial bus, follows an addressing system called a CSR structure (ISO/IEC 13213:1994). Also, the 1394 is imply used in a plug-and-play system, and provides an isochronous transmission system for multimedia services and an asynchronous transmission system for management. Transfer rates of 100 Mbps, 200 Mbps and 400 Mbps are already available, and a 800 Mbps transfer rate and a gigabit transfer rate are expected to be available in IEEE 1394.
International Engineering Task Force (IETF) has been discussing an IP over the 1394 (IPover1394) to accomplish compatibility of TCP/IP (transmission control protocol/Internet protocol) with the 1394, and the IP over 1394 enables Internet access or the like. Here, the 1394 acts as the link and physical layers of a TCP/IP suite. The 1394 can also connect a digital home appliance, a computer and its peripheral apparatuses to one network and can guarantee QOS (Quality of Services), thus receiving attention as a home LAN.
The gateway of FIG. 1 includes a 1394 protocol layer 100 for processing a received 1394 signal or processing a received signal into a 1394 signal, an ATM protocol layer 110 for processing a received ATM signal or processing a received signal into an ATM signal, and an IP layer 120 for processing IP data received from the 1394 protocol layer 100 or ATM protocol layer 110.
The 1394 protocol layer 100 is comprised of a 1394 physical layer 101, a 1394 link layer 102, a transaction layer 103, a 1394 mapping layer 104 and an IP over 1394 (IPover1394) layer 105. The 1394 physical layer 101 is connected to an IEEE 1394 bus and transmits or receives a physical signal therethrough. The 1394 link layer 102 makes a data packet by attaching a header or the like to a signal received from the 1394 physical layer 101. The transaction layer 103 is a protocol layer for processing a 1394 asynchronous packet. The 1394 mapping layer 104 facilitates use of the 1394. The IP over 1394 layer 105 fragments an IP datagram and reassembles the IP diagram fragments according to the IP over 1394 under discussion.
The ATM protocol layer 110 is comprised of an ATM physical layer 111, an ATM link layer 112, an ATM mapping layer 113, a signaling layer 114, and an IP over ATM (IPoverATM) layer 115. The ATM physical layer 111 is connected to an ATM network data bus and transmits or receives physical or electrical signals therethrough. The ATM link layer 112 attaches a predetermined header to data received from the ATM physical layer 111 and transfers the resultant data. The ATM mapping layer 113 cuts data into pieces of data suitable for the ATM. The signaling layer 114 sets a virtual channel VC and a virtual path VP in the ATM. The IP over ATM layer 115 performs conversion such as obtaining an ATM address corresponding to an IP address. The IP layer 120 routs the IP datagram.
In the operation of the conventional gateway of FIG. 1, when data is transmitted from the 1394 to the ATM, an IP datagram received via the 1394 network in the gateway is reassembled by the IP mapping layer 104 and the IP over 1394 layer 105 and provided to the IP layer 120. The IP layer 120 searches for a path for the destination address of the data in a predetermined routing table. A virtual channel and a virtual path are obtained by the IP over ATM layer 115 and the signaling layer 114, and the IP datagram is processed into ATM cells through the ATM mapping layer 113, the ATM link layer 112 and the ATM physical layer 111, and then the data cells are transmitted to the ATM network. On the other hand, when data is transmitted from the ATM to the 1394, data cells received from the ATM in the gateway are reassembled and provided to the IP layer 120. The IP layer 120 detects a 1394 node ID corresponding to the destination address of the data, converts the data into a 1394 signal format, and transmits the resultant data to the detected node ID in the 1394 network.
As described above, the conventional protocol must be controlled by network layers in order to transmit signals between different networks, which wastes time and memory resources due to the processing operation of a central processing unit (CPU) and the copying operation of a memory for the above control operation.
To solve the above problem, it is an object of the present invention to provide a method of forming a network path, by which a connection of data stream to be transferred between two different networks is set up early during data transmission upon connection between the networks, and then data repetition is accomplished in the second layer of each network according to the set connection without need to use a CPU for each packet when a gateway for mediating networks transmits data.
To achieve the above object, the present invention provides a method of transferring data between networks comprising the steps of: storing a connection path which is set between predetermined data from a first network and a predetermined address in a second network during initial connection between the first and second networks; and transferring the predetermined data from the first network along the stored path.
It is preferable that transfer of the predetermined data from the first network along the stored path is network layer 2 switching transmission.
To accomplish the above object, the present invention provides a method of transferring data between networks in a gateway for connecting an IEEE 1394 network to another predetermined network, the method comprising the steps of: (a) storing a data movement path set between the channel number of initial channel data generated by the IEEE 1394 network and the other network to which the data is to be transferred; and (b) transferring subsequent data of the same channel from the 1394 network along the stored data movement path.
It is preferable that the step (a) comprises the substeps of: setting the relationship between a channel number from the 1394 network and a predetermined memory area in the second protocol layer for the 1394 network; and storing a connection setup path from the 1394 network to the other network, as well as the predetermined memory area position associated with the connection setup path, in the second protocol layer for the other network.
It is preferable that the step (b) comprises the substeps of: storing data of the same channel transmitted from the 1394 network in the set memory area; and transferring the data stored in the memory area along the connection setup path, which is mapped with the memory area and stored in the second protocol layer for the other network.
Preferably, the other network is an asynchronous transfer mode (ATM) network.
It is preferable that the link layer for the ATM network stores the memory area, and a connection-setup virtual channel and a connection-setup virtual path.
Also, it is preferable that data of a predetermined channel transmitted from the IEEE 1394 network is stored in a predetermined memory area set in the 1394 link layer after initial connection setup, and the data in the memory area is moved to the link layer for the ATM network and transferred to an address in the ATM network along a virtual channel and a virtual path which are set by mapping to the memory area in the link layer for the ATM network.